Automatic device for removing resistance in starting electric motors and replacing same



.1.. e e h. s t e e h S 2 M A H G N I T ml. I H W H. G. u d 0 M 0 /N\AUTOMATIC DEVICE FOR REMOVING RESISTANCE IN STARTING ELECTRIC MoToRs ANDREPLAGING SAME.

Patented Apr. 24, 1894.

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N. D. c.

(No Model.) 2 Sheets-Sheet' 2.

. G. H. WHITTINGHAM.

AII-TOwkAIgIGjlDLEVIQE FOB. REMOVINGRBSISTANGBIN- STARTING 1.1i=-ELEGTRIG ,MQTORS AND REPLAGING SAME.

NO. 518,906. Patented Apr. 24, 1894.

UNITED STATESv PATENT OFFICE.

GEORGEI-I. VVI-IITTINGHAM, OF BALTIMORE, MARYLAND, ASSIGNOR TO THEAUTOMATIC SWITCH COMPANY OF BALTIMORE CITY, OF MARYLAND.

AUTOMATIC DEVICE FOR REMOVING RESISTANCE IN STARTINGv ELECTRIC MOTORSAND REPLACING SAME.

SPECIFICATION forming part of Letters Patent No. 518,906, dated April24, 1894.

Application filed April 4, 1893. Serial No. 469.032. (No model.)

.T0 aZZ whom, it may concern:

Be it known that I, GEORGE H. WHITTING- HAM, a citizen of the UnitedStates, residing at Baltimore, in the State of Maryland, have inventedcertain new and useful Improvements in Automatic Devices for RemovingResistance in Starting Electric Motors and Replacing the Same, of whichthe following is a specication.

This invention relates to an automatic starting device for electricmotors and has for its object to gradually reduce the resistance in thearmature circuit of the motor automatically when the current is turnedon and the motor starting by cutting out the coils of resistance oneafter the other from that of the greatest resistance to that of theleast resistance, and maintaining it in this position during the runningof the motor, so that when the circuit through the motor is rstcompleted to start the motor the current will meet with the greatestresistance and when the motor is fully running there will be the leastresistance to the passage of the current. This is done to prevent theburning out of the armature of the motor when starting. When the currentis shut-off this device operates to automatically replace the resistancein the circuit in readiness to be started again. By my invention thepower for operating the resistance-controlling device is obtained fromthe motor itself.

In order to make the improvements clearly understood I have shown in theaccompanying drawings means for carrying the same into practical effect,without however intending to limit my invention to this particularconstruction, for the invention as broadly conceived by me and asdefined in my claims, may be embodied in many other forms.

In the drawings-Figure 1 shows an end View of a motor provided with myimproved automatic resistance controlling device. Fig. 2 is a horizontalsection of the device taken on the line 2--2 of Fig. 1. Fig. 3 is asection through the resistance plates taken on line 3--3 of Fig. 1. Fig.shows a diagram of the circuits.

The letter, A, designates the field-magnets of the motor and A', thecoils thereof.

B, designates the armature and B, the armature-shaft which is journaledin bearings, C', on the base, C, of the motor.

Asuitableupwardly-projectingframe-work, D, is bolted to the outside ofthe bearingblock, C and base, C, at the commutator end of the motor.Mounted on this frame-work, D, is a segment-shaped ratchet bar, G; aholding pawl, f; and electro-magnets, I-I, all hereinafter referred to.

I, designates the commutator brushes.

In the present instance the commutator end of the armature shaft, B', isextended beyond the outside of the bearing-block C', and has mountedthereon an eccentric, E, fastened by a-key, a; around this eccentric isa split eccentric strap comprising two parts, b, b', held together bysuitable bolts, b3. The upper half, b, of the eccentric strap has athreaded socket, b2, to receive one end of an eccentric rod, E, on theother end of which is mounted a yoke, F, having two arms, c. The ratchetpawl, G, is pivoted on a pin, d', between the said arms, c, and its freeend engages the teeth, d, of the segment-shaped ratchet bar, G,connected with a hub which is pivoted on a stud, e, fixed to theupwardly-extending frame,D. The ratchet teeth, d, extend along only aportion of the length of the bar, G, and the remainder 'nas a smoothsurface. The ratchet-pawl previously referred to, has a depending arm,cl2, which engages the free end of a leaf-spring, d3, attached to theyoke, F, the function of this spring is to keep the pawl in engagementwith the teeth of the ratchet-bar, G. A holding pawl,]f, pivoted on astud,f, also on the frame D, has a hook" end, f2, to also engage theteeth, d, of the segment ratchet bar, G. This pawl has a depending arm,f3, to engage the ratchet pawl, G', for a purpose hereinafter described.Apair of electro-magnets, H, have position on the frame, D, opposite thesegment-ratchet bar, G, one end of each magnet core, g, being fastenedin a rib or ange, g', extending across the fixed ends of the magnets,said flange, g' ,being integral with the frame, D. Alongitudinally-movable rod, .T ,passes between the electro-magnets andone end extends through theflange, g', which forms one bearing therefor.This extending end of the rod, J, is provided with a head, J 2, having alateral hole which receives a cross- IOO pin, t'. A pair of link-plates,L, one at each side of the head, J 2, have one end piveted en the pin,fi, and the other on the pin, d', between the ratchet-pawl, G', andthearms, c, of the yoke, F.v An additional bearing, C2, on the frame,D, isprovided for the other end ot the rod, J. An armature, J', is fixed onthe rod, J, between its bearings, g', g2, and extends crosswise of thesame and coacts with the electro-magnets, Il. A spiral-spring, 7i,around the rod, J, is interposed between the iiange, g', and armature,J', and serves to keep the armature normally away from the magnets, lvl.It will be seen that when the magnets, H, are not energized thearmature, J', will not only be away from the magnets but theratchet-pawl, G', and holding pau/Lf, will be disengaged from the teethof the ratchetbar, G, which is thereby allowed to fall against asuitable stop, D', on the frame D. A contact-shoe, M, made up of aseries of plates, j, adjacent to one another is pivoted on an arm, N,attached to the segment-shaped bar, G, but insulated therefrom. A plate,j', of spring material, has one edge iixed te the said pivotarm, N, andits other edge slitted to form a series of spring tangs,j2, each ofwhich bears on acorresponding plate,j, of the contact shoe, M. A seriesof contact plates, t, 7o', k2, dce., insulated from each other arerespectively connected with a resistance coil, O. These contact platesare mounted on the frame, D, on an arc described from the pivot stud, c,and are successively engaged by the contactshoe, M, which however, isalways in engagement with one of them.

The operation is as follows:-When the motor is connected with the line,Z, Z', by moving the switch, P, the current will flow along the line, m,through the shoe, M, resistance coil, O, armature, B, then along theline, m', back to the switch; the current will also flow from line, m,along line, it, coil, A', of fieldinagnet and then return to line, m',along line, fa; another portion of the current from main line, m, willflow along line, o, to electro-magnets, H, and then return along line,0', t0 line, 'm'. The current by iiowing as just stated will energizethe field magnets and armature of the motor and at same time the electromagnets, Il, which will attract and move the armature, J', against theaction of the spring, h, whereby the pawls, G', and j', are brought intoengagement with the teeth ot the ratchet bar, G. New as the current hasalso gone to the held-magnets and armature, the latter will be caused torotate with its shaft, imparting motion to the eccentric which in turnreciprocates the eccentric-rod and pawl, G', which latter lifts theratchet bar, G, one tooth at a time until the smooth surface of theratchet bar reaches the said pawl whereupon the upward movement ceases;the holding pawl, f, coacting with and holding the bar elevated as theratchet pawl, G', reti-acts. By this intermittent upward movement theshoe, M, connected with the ratchet bar, G, is moved over the contactplates et the resistance coil, beginning with the one of greatestresistance and gradually diminishing until the last plate is reachedwhere there is practically no resistance. Vhen the shoe, M, has reachedthis last plate, 7c', the pawl, G', simultaneously reaches the smoothsurface on the ratchet bar, G, and consequently will not lift the barany higher. lVhen the shoe, M, has reached this last plate, 7a2-thepoint of lowest resistance-the said circuit is maintained thereat duringthe run of the motor. lt will new be seen that when the current is shuto'll' by the switch, P, the field-magnets, armature and electro-magnetswill become inert, and consequently the pawls, G', and f, be disengagedfrom the ratchet bar, G, which will then fall and the shoe, M, againbrought into contact with the plate, it, indicating the greatestresistance of the coil, whereupon the apparatus is in readiness foragain starting the motor. It is obvious that a second pair ofelectro-magnets, lvl', indicated by broken lines in Figs. l and Ll,could be placed in the circuit with the electro-magnets, H, andenergized simultaneously therewith; this second pair ot' magnets wouldalso be mounted on the frame, D, and would attract an armature Q', inbroken lines, rigid on one arm of the ratchet bar, G, so that when thepawl, G', has raised the ratchet bar, G, as high as it can and is inengagement with the tooth adjoining the smooth surface; the magnet, ll',will elevate the bar slightly higher to prevent the pawl hammering upagainst the said last tooth, but allow it to play freely on the smoothsurface et the ratchet bar. It will also be seen that instead ofconnecting the start;- ing and stopping mechanism as here shown, itcould be driven independently, that is-a small motor could be employedand an independent circuit for this auxiliary motor and theelectro-magnets, H, used, but said circuit made simultaneous with theone tllrough the main motor which latter circuit passes only through theshoe, M, and resistance coil, O, ot the starting mechanism. The two arein other respects independent of one another. It will be furtherobserved that the two could be connected up mechanically, as forinstance by a belt from the motor driving a shaft on which the eccentricis mounted and the electro-magnets suitably connected in the linecircuit as it leaves the switch.

It will new be seen that the main object of my invention is to providean automatic de vice for cutting out gradually the resistance to thecurrent flowing tothe motor when the same is turned on, so that when themotor is fully running there will be practically no resistance to thepassage of the current, and when the current is shutoff te againintroduce the said resistance automatically in readiness for againstarting. By this means et' controlling the flow of the current, themotor will always be governed by its load, that is-when the load isheavy the resistance IOO IIO

will slowly and gradually be cut out or diminished until the full speedand power is obtained, the motor starting up slowly, but when the loadis light the motor will start up fast and the resistance rapidly cut-outor diminished thus allowing the motor to speed up quickly.

Having described my invention, I claiml. In an automatic starting devicefor electric motors, the combination of a motor; a resistance in serieswith the armature when starting the motor; a contact shoe engaging theresistance; and a direct mechanical con nection between the armature andthe contact shoe, whereby each revolution of the armature imparts to thecontact shoe a positive movement and gradually cuts out the resistancefrom the armature circuit and maintains said circuit at the point oflowest resistance during the run of the motor.

2. The combination of a motor; a resistance coilin electrical connectionwith the armature; a movable contact device in circuit with said coil; apawl and ratchet operated by the motor armature and adapted to impart tothe contact device a limited movement in the direction which reduces theresistance of the armature circuit; and means for disengaging the pawland ratchet when the supply of electricity is cut off.

3. In an automatic starting device for electric motors, the combinationof a motor; a resistance in series with the armature when starting themotor; a contact shoe engaging the resistance; a direct mechanicalconnection between the armature and the contact shoe which is operativein the direction of cutting out the resistance from thearmature-circuit, whereby said circuit is maintained at the point oflowest resistance during the run of the motor; and further means wherebythe cessation of the current disengages the said mechanical connectionand allows the contact shoe to return to its original position where thehighest resistance is replaced, for the purpose set forth.

et. In an automatic starting device for electric motors, the combinationof the iield magnets; the armature; aresistance coil in series with thearmature; a series of contact plates connected with the said coil; amovable ratchet bar; a contact shoe connected with said bar and movableover said contact plates; a ratchet pawl actuated by the armature; andmeans for causing the ratchet pawl to engage said ratchet bar and impartto it an intermittent movement only in the direction which reduces theresistance of the armature circuit, for the purpose set forth.

5. In a resistance controlling device for electric motors, thecombination of the fieldmagnets; the armature; a resistance coil; a

series of contact-plates each connected with the said coil; a movableratchet bar; a contact-shoe connected with the said ratchet bar andmoving over the contact plates successively; said field-magnets,armature; resistance coil and contact shoe all being connected with aline circuit; a reciprocating ratchet pawl to engage the said ratchetbar and 1mpart an intermittent movement to it and the contact shoe; andmeans to disengage the pawl from the ratchet bar when the motor circuitis broken to allow the ratchet bar and contact shoe to return to theirnormal position.

6. In a resistance controlling device for electric motors, thecombination of the fieldmagnets; the armature; the armature shaft; aresistance coil; a series of contact plates each connected with the saidcoil; a contact shoe to engage the said plates and in circuit with theresistance coil, field-magnets, armature and line circuit; a movableratchet bar; a ratchet pawl to engage the ratchet bar and impart anintermittent movement to it and to the contact shoe; an eccentric on thearmature shaft to reciprocate the ratchet pawl; a spring to co-act withthe ratchet pawl and keep it away from the ratchet bar; and anelectro-magnet energized simultaneously with the field-'magnets andarmature to co-act with the said` ratchet pawl and place it intoengagement with the ratchet bar against the action of the spring.

7. In a resistance controlling device for electric motors, thecombination of the eldmagnets ;-the armature; the armature shaft; aresistance coil; a series of contact plates each connected with theresistance coil; a contact shoe to engage the said plates and in circuitwith the :resistance coil, field-magnets,

.armature and line circuit; a movable segment-shaped ratchet bar; aratchet pawl to engage the ratchet bar and impart an intermittentmovement to it and to the contact shoe; an eccentric on the armatureshaft to ICC reciprocate the ratchet pawl; a spring to cov GEORGE n.WHITTINGHAM.

Witnesses: A. O. BABENDREIER,

CHAs. B. MANN, J r.

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